diff --git a/features/formatters/regression_tests.feature b/features/formatters/regression_tests.feature
index 11843f4e81..70248a81be 100644
--- a/features/formatters/regression_tests.feature
+++ b/features/formatters/regression_tests.feature
@@ -44,6 +44,12 @@ Feature: Regression tests for legacy custom formatters
      And the output should contain "6 examples, 3 failures, 1 pending"
      But the output should not contain any error backtraces
 
+  Scenario: Use rspec-instafail formatter
+    When I run `rspec --format RSpec::Instafail`
+    Then the output should contain "6 examples, 3 failures, 1 pending"
+     And the output should contain "The RSpec::Instafail formatter uses the deprecated formatter interface"
+     But the output should not contain any error backtraces
+
   @wip @announce
   Scenario: Use nyancat formatter
     When I run `rspec --format NyanCatFormatter`
diff --git a/rspec-core.gemspec b/rspec-core.gemspec
index e0cbb916b6..6fcff7f75a 100644
--- a/rspec-core.gemspec
+++ b/rspec-core.gemspec
@@ -53,4 +53,5 @@ Gem::Specification.new do |s|
   # For legacy custom formatter regression tests
   s.add_development_dependency "fuubar",             "1.3.2"
   s.add_development_dependency "nyan-cat-formatter", "0.5.2"
+  s.add_development_dependency "rspec-instafail",    "0.2.4"
 end